var tkx_img = document.querySelector('.tkx2>img');
var sgm = document.querySelector('.songGongMing');
var sgm_img = document.querySelector('.songGongMing>img');

tkx_img.onclick = function(){
    sgm.style.display = 'block'
}
sgm_img.onclick = function(){
    sgm.style.display = 'none'
}